If blood is dropped directly vertical from the surface without any movement, the angle of impact will be ) . Select one: a. 45^circ b. 30^circ C. 0^circ d. 100^circ e. 90^circ

The correct answer is e. $90^{\circ }$.<br /><br />When blood is dropped directly vertical from the surface without any movement, the angle of impact will be $90^{\circ }$. This is because the blood is falling straight down, perpendicular to the surface, resulting in a $90^{\circ }$ angle between the direction of the blood's motion and the surface.